refactor(lsp): Use internal ChildProcess module for launching languag…

…e servers (#6374)

## Problem
- we want to use internal ChildProcess module over node's child process
module
- some code for spawning the language server is duplicated between the
workspace server and the amazon q server

## Solution
- use internal ChildProcess module and de-dup the common language server
spawning code

---

- Treat all work as PUBLIC. Private `feature/x` branches will not be
squash-merged at release time.
- Your code changes must meet the guidelines in
[CONTRIBUTING.md](https://github.com/aws/aws-toolkit-vscode/blob/master/CONTRIBUTING.md#guidelines).
- License: I confirm that my contribution is made under the terms of the
Apache 2.0 license.

packages/amazonq/src/lsp/client.ts

@@ -5,18 +5,17 @@
 
 import vscode, { env, version } from 'vscode'
 import * as nls from 'vscode-nls'
-import * as cp from 'child_process' // eslint-disable-line no-restricted-imports -- language server options expect actual child process
 import * as crypto from 'crypto'
 import { LanguageClient, LanguageClientOptions, ServerOptions, TransportKind } from 'vscode-languageclient'
 import { registerInlineCompletion } from '../inline/completion'
-import { AmazonQLspAuth, notificationTypes, writeEncryptionInit } from './auth'
+import { AmazonQLspAuth, encryptionKey, notificationTypes } from './auth'
 import { AuthUtil } from 'aws-core-vscode/codewhisperer'
 import { ConnectionMetadata } from '@aws/language-server-runtimes/protocol'
-import { ResourcePaths } from 'aws-core-vscode/shared'
+import { ResourcePaths, createServerOptions } from 'aws-core-vscode/shared'
 
 const localize = nls.loadMessageBundle()
 
-export function startLanguageServer(extensionContext: vscode.ExtensionContext, resourcePaths: ResourcePaths) {
+export async function startLanguageServer(extensionContext: vscode.ExtensionContext, resourcePaths: ResourcePaths) {
     const toDispose = extensionContext.subscriptions
 
     // The debug options for the server
@@ -31,19 +30,21 @@ export function startLanguageServer(extensionContext: vscode.ExtensionContext, r
         ],
     }
 
-    const serverPath = resourcePaths.lsp
+    const serverModule = resourcePaths.lsp
 
     // If the extension is launch in debug mode the debug server options are use
     // Otherwise the run options are used
     let serverOptions: ServerOptions = {
-        run: { module: serverPath, transport: TransportKind.ipc },
-        debug: { module: serverPath, transport: TransportKind.ipc, options: debugOptions },
+        run: { module: serverModule, transport: TransportKind.ipc },
+        debug: { module: serverModule, transport: TransportKind.ipc, options: debugOptions },
     }
 
-    const child = cp.spawn(resourcePaths.node, [serverPath, ...debugOptions.execArgv])
-    writeEncryptionInit(child.stdin)
-
-    serverOptions = () => Promise.resolve(child)
+    serverOptions = createServerOptions({
+        encryptionKey,
+        executable: resourcePaths.node,
+        serverModule,
+        execArgv: debugOptions.execArgv,
+    })
 
     const documentSelector = [{ scheme: 'file', language: '*' }]
 

packages/core/src/amazonq/lsp/lspClient.ts

@@ -10,7 +10,6 @@
 import * as vscode from 'vscode'
 import * as path from 'path'
 import * as nls from 'vscode-nls'
-import { spawn } from 'child_process' // eslint-disable-line no-restricted-imports
 import * as crypto from 'crypto'
 import * as jose from 'jose'
 
@@ -30,27 +29,13 @@ import {
     GetRepomapIndexJSONRequestType,
     Usage,
 } from './types'
-import { Writable } from 'stream'
 import { CodeWhispererSettings } from '../../codewhisperer/util/codewhispererSettings'
-import { ResourcePaths, fs, getLogger, globals } from '../../shared'
+import { ResourcePaths, createServerOptions, fs, getLogger, globals } from '../../shared'
 
 const localize = nls.loadMessageBundle()
 
 const key = crypto.randomBytes(32)
 
-/**
- * Sends a json payload to the language server, who is waiting to know what the encryption key is.
- * Code reference: https://github.com/aws/language-servers/blob/7da212185a5da75a72ce49a1a7982983f438651a/client/vscode/src/credentialsActivation.ts#L77
- */
-export function writeEncryptionInit(stream: Writable): void {
-    const request = {
-        version: '1.0',
-        mode: 'JWT',
-        key: key.toString('base64'),
-    }
-    stream.write(JSON.stringify(request))
-    stream.write('\n')
-}
 /**
  * LspClient manages the API call between VS Code extension and LSP server
  * It encryptes the payload of API call.
@@ -197,19 +182,19 @@ export async function activate(extensionContext: ExtensionContext, resourcePaths
 
     const serverModule = resourcePaths.lsp
 
-    const child = spawn(resourcePaths.node, [serverModule, ...debugOptions.execArgv])
-    // share an encryption key using stdin
-    // follow same practice of DEXP LSP server
-    writeEncryptionInit(child.stdin)
-
     // If the extension is launch in debug mode the debug server options are use
     // Otherwise the run options are used
     let serverOptions: ServerOptions = {
         run: { module: serverModule, transport: TransportKind.ipc },
         debug: { module: serverModule, transport: TransportKind.ipc, options: debugOptions },
     }
 
-    serverOptions = () => Promise.resolve(child!)
+    serverOptions = createServerOptions({
+        encryptionKey: key,
+        executable: resourcePaths.node,
+        serverModule,
+        execArgv: debugOptions.execArgv,
+    })
 
     const documentSelector = [{ scheme: 'file', language: '*' }]
 

packages/core/src/shared/index.ts

@@ -64,3 +64,4 @@ export * from './lsp/lspResolver'
 export * from './lsp/types'
 export { default as request } from './request'
 export * from './lsp/utils/platform'
+export * as processUtils from './utilities/processUtils'

packages/core/src/shared/lsp/utils/platform.ts

@@ -3,6 +3,51 @@
  * SPDX-License-Identifier: Apache-2.0
  */
 
+import { ToolkitError } from '../../errors'
+import { ChildProcess } from '../../utilities/processUtils'
+
 export function getNodeExecutableName(): string {
     return process.platform === 'win32' ? 'node.exe' : 'node'
 }
+
+/**
+ * Get a json payload that will be sent to the language server, who is waiting to know what the encryption key is.
+ * Code reference: https://github.com/aws/language-servers/blob/7da212185a5da75a72ce49a1a7982983f438651a/client/vscode/src/credentialsActivation.ts#L77
+ */
+function getEncryptionInit(key: Buffer): string {
+    const request = {
+        version: '1.0',
+        mode: 'JWT',
+        key: key.toString('base64'),
+    }
+    return JSON.stringify(request) + '\n'
+}
+
+export function createServerOptions({
+    encryptionKey,
+    executable,
+    serverModule,
+    execArgv,
+}: {
+    encryptionKey: Buffer
+    executable: string
+    serverModule: string
+    execArgv: string[]
+}) {
+    return async () => {
+        const lspProcess = new ChildProcess(executable, [serverModule, ...execArgv])
+
+        // this is a long running process, awaiting it will never resolve
+        void lspProcess.run()
+
+        // share an encryption key using stdin
+        // follow same practice of DEXP LSP server
+        await lspProcess.send(getEncryptionInit(encryptionKey))
+
+        const proc = lspProcess.proc()
+        if (!proc) {
+            throw new ToolkitError('Language Server process was not started')
+        }
+        return proc
+    }
+}

packages/core/src/shared/utilities/processUtils.ts

@@ -389,6 +389,10 @@ export class ChildProcess {
         return this.#processResult
     }
 
+    public proc(): proc.ChildProcess | undefined {
+        return this.#childProcess
+    }
+
     public pid(): number {
         return this.#childProcess?.pid ?? -1
     }